Targeted editing of intronic-splicing silencer enhancement of SMN2 Exon 7 inclusion by CRISPR/Case 9

Spinal muscular atrophy(SMA)is an autosomal recessive hereditary neuromuscular disease.Exon 7 and 8 of survival of motor neuron 1(SMN1)gene or only exon 7 homology deletion leads to the failure to produce a full-length SMN gene.The copy number of SMN2 gene with high homology of SMN1 affects the degree of disease and was the target gene for targeting therapy,in which splicing silencer in intron 7 was the key to suppress the inclusion of exon 7.In this study,we projected to use CRISPR/Case 9 for the targeted editing of intronic-splicing silencer(ISS)sequence to promote the inclusion of SMN2 exon 7 and increase the production of SMN2 full-length(FL)gene expression.It happens that there was a protospacer adjacent motif(PAM)at one end of the ISS sequence according to the design of sgRNA.The recombinant vector of sgRNA HSMN2 CRISPR/Case 9 was constructed and transfected into HEK293 cells.Sequencing results showed that the ISS sequence could be edited accurately and targeting in the predicted direction,in which deleting small fragments,inserting small amounts and mutation.Quantitative analysis of RT-PCR products by restriction enzyme of DdeI digestion showed that the FL of SMN2 increased by 8%(P<0.05).In the primary cultured chondrocytes of SMA mice,in which sgRNA HSMN2 CRISPR/Case9 recombinant vector transfection could increase the SMN2 FL gene by 23%(P<0.05)and significantly improve SMN protein levels(P<0.05).CRISPR/Case 9 is an effective tool for gene editing and therapy of hereditary diseases,but it is rarely reported in the treatment of SMA diseases.This study shows that CRISPR/Case 9 was first used for the precision target of ISS sequence editing,which can effectively promote the production of SMN2 FL gene expressions,in which there was an important clinical reference value.

一颗大质量恒星在死亡前猛烈抛射出星周物质

Ⅱ型超新星是宇宙中最常见的恒星爆炸,其富氢的大质量前身星最后阶段的演变让人捉摸不透.这类恒星晚期演化和由此产生的星周环境的差异导致了超新星丰富的观测多样性.为了建立Ⅱ型超新星爆炸与大质量恒星晚期演化之间的联系,有必要捕捉超新星爆炸的第一缕光,即由激波爆发冷却产生的高能光子电离星周物质造成的闪亮光谱.近邻星系M 101中爆发的SN 2023ixf为探索这个问题提供了难得的机会.本文利用爆炸后1~5天内频繁拍摄地闪亮光谱,对这颗超新星周围物质的性质进行严格的约束.计算得出,SN 2023ixf前身星在爆炸前最后2~3年中以高达M≈6×10^(-4)M⊙a^(-1)速率损失物质.这些物质以55 km s^(-1)的速度运动,在距离前身星不到7×10^(14)cm的位置形成致密的星周物质壳层.考虑到如此高的质量损失率和相对较大的风速,以及20年前的前身星图像,SN2023ixf可能是刚从红超巨星演化而来的黄巨超巨星产生的超新星爆炸.